Method and Device for Connecting a Pipe to a Confinement of a Subsurface Borehole

ABSTRACT

Method and apparatus are for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement. The method includes: providing an expandable metallic bladder element, that by use of a fluid is expandable between an unexpanded and an expanded position, in a sector of the annulus; and expanding the metallic bladder element.

BACKGROUND

There is provided a method for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement. The invention also includes a device for connecting the pipe to the confinement of the sub-surface borehole.

The confinement may be in the form of a formation wall, a surrounding pipe, or a room in any other kind of equipment that is positioned in the borehole.

It is normal procedure to fix a pipe that is running through a subsurface borehole at its lower party in order to keep the pipe in a fixed position relative the confinement. The reason may be for anchorage of sensors, a whipstock or other equipment that do not need pressure insulation. Other purposes are to anchor pipes that are exposed to temperature changes such as water injectors and stimulated wells. It is also normal procedure to fix a pressure isolating packer to the borehole.

When fluid of a different temperature to that of the borehole is flowing through a relative long pipe in the borehole, large temperature induced forces are set up in the connections between the borehole and the confinement. Forces of up to a couple of hundred tons have been experienced.

Traditionally, inflatable packers have been used for this fixation purpose. Known packers are not designed to carry heavy axial forces as the axial forces have to be sustained by the end portions of the packer. No axial forces are transmitted through the inflation part of the packer.

It may also be inconvenient to close the annulus completely.

In order to overcome these and other disadvantages, slips that are made to engage with the confinement have been employed. The drawback of these are that they have a relative short contact length along the confinement and are thus not suitable in all open hole situations, particularly those with weak rock in the formation.

U.S. Pat. No. 2,783,028 discloses a drill stem supporter and stabilizer where an outer and an inner shoe are activated relatively each other by an inflatable tube that is filled from a local gas cylinder.

DE document 2841819 shows a telescopic connection where a pneumatic tube forces a resilient ring part against an inner tube.

EP document 2 184 436 discloses a placement of a conduit through an expandable packer.

US documents U.S. Pat. No. 3,401,946 and 2001/0045699 as well as WO 2006/118470 show equipment where bladders made from resilient material are expandable in a confinement.

Bladders made from resilient material, such as natural or synthetic rubber, will immediate loose their shape if a leakage develops. They are also subjected to diffusion of fluid through the bladder wall and thus reduced bladder pressure over time.

SUMMARY

The purpose of the invention is to overcome or reduce at least one of the disadvantages of the prior art.

The purpose is achieved according to the invention by the features as disclosed in the description below and in the following patent claims.

According to a first aspect of the invention there is provided a method for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement, wherein the method includes:

-   -   providing an expandable metallic bladder element, that by use of         a fluid is expandable between an unexpanded and an expanded         position, in a sector of the annulus; and     -   expanding the metallic bladder element.

By providing a metallic bladder element, some of the weaknesses of elastic bladder elements will be overcome. As the metallic bladder element during expansion is permanently deformed, it will not, unlike elastic bladder elements, loose all deformation if a leakage of expansion fluid should develop. Further, by use of a metallic packer element, no fluid is lost through diffusion of fluid through the wall of the metallic bladder element.

The method may include providing a toothed or non toothed anchor that in its engaged position, when the metallic bladder element is expanded, has an ability to transfer axial load between the pipe and the confinement.

The weakness of conventional expandable packers with respect to transfer of axial forces is thus overcome by letting an anchor carry the axial load while the metallic bladder element carries a radial load. The length of the anchor may be more than five times the pipe diameter. It is foreseen that lengths of between 5 and 60 times the pipe diameter are preferable in order to spread the axial force along the confinement, particularly when the confinement is an open hole.

The metallic bladder element may be expanded by use of a liquid. It is foreseen that hydraulic expansion will be most suitable as relatively high pressures may be utilized.

According to a second aspect of the invention there is provided an apparatus for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement, wherein an expandable metallic bladder element, that by use of a fluid is expandable between an unexpanded and an expanded position, is positioned in a sector of the annulus.

The width and length of the metallic bladder element have to be adapted to the actual usage. It is likely that the width may be in the region between 25 mm and 500 mm, while the length may be several meters. Wall thickness will be from say one millimeter up to four millimeter depending on local requirements such as available expansion pressure and required force from a permanently deformed metal bladder element.

The metallic bladder element may be made from a flattened pipe, see the special part of the description. It is also possible to make the metallic bladder elements from two elongated plates that are welded or braced together along each side. Ductile steel such as stainless steel is a suitable material.

The expandable metallic bladder element may be helically wound around the pipe.

An anchor that in its engaged position has an ability to transfer axial load between the pipe and the confinement may be positioned in the annulus. The metallic bladder element may in its expanded position engage the anchor.

The metallic bladder element and the anchor may be positioned on opposite sides of the pipe.

The metallic bladder element and the anchor may in some cases be positioned on the same side of the pipe.

The metallic bladder element may be positioned in the anchor. The anchor may be made to engage by relative movement between at least a first and a second member of the anchor. The axial forces acting between the first and second member may be transferred between the first and second member via at least one hinge, a biasing element, a contact surface or another suitable element known to a skilled person.

The pipe itself may constitute the anchor by being forced towards the confinement by the metallic bladder element.

The anchor may for special purposes be made from an elastic material, and may in those cases work as a pressure sealing packer.

The anchor may be made from a combination of elastic and metallic material.

The anchor may be made from a material that is swellable in a wellbore fluid.

The metallic bladder element may be positioned in an elastic material. This is useful when the annulus is to be closed off for fluid flow.

A pressurized fluid reservoir may be connectable to the metallic bladder element. The metallic bladder element may thus be expanded by fluid from a local source.

The metallic bladder element may at least partly be filled with particles. When the metallic bladder element is expanded, the particles will move into the available space and thus prevent the metallic bladder from retracting in the region of the particles should the expansion pressure disappear.

As explained in the general part of the description the method and apparatus according to the invention overcomes some of the disadvantages of prior art. The method and apparatus will thus be particularly useful under difficult operations in a borehole where the pipe has to be anchored to the borehole or the annulus has to be closed.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, an example of a preferred method and apparatus is explained under reference to the enclosed drawings, where:

FIG. 1 shows in perspective and a partly sectioned view a pipe that is positioned in a subsurface borehole where an apparatus according to invention for connecting the pipe to the confinement is provided;

FIG. 2 shows a section I-I from FIG. 1 prior to expansion of a metallic bladder element;

FIG. 3 shows a principal sketch of a section of a metallic bladder that is filled with particles;

FIG. 4 shows a principal sketch where a fluid reservoir is connected to the metallic bladder element;

FIG. 5 shows the same as FIG. 2, but after the metallic bladder element has been expanded;

FIG. 6 shows an embodiment where more than one metallic bladder elements are utilized;

FIG. 7 shows an embodiment where the metallic bladder elements are overlapping;

FIG. 8 shows an embodiment where the metallic bladder elements have an elastic material outside;

FIG. 9 shows an embodiment where the metallic bladder element is helically wound around the pipe;

FIG. 10 shows an embodiment where the pipe is biased towards the confinement.

FIG. 11 shows an embodiment where the metallic bladder element is position in an anchor; and

FIG. 12 shows a section XI-XI in FIG. 11.

DETAILED DESCRIPTION OF THE DRAWINGS

On the drawings the reference number 1 denotes a pipe that is positioned in a borehole 2 in a confinement 4 in the form of a formation. An anchor 6, here in the form of a several meter long bar, is positioned in an annulus 8 between the pipe 1 and the confinement 4.

A hydraulically expandable metallic bladder element 10 is positioned at the opposite side of the pipe 1 relative to the anchor 6. The metallic bladder element 10 may take the form of a flattened pipe that is closed and its end portions 12 as shown in FIG. 3.

A fluid pipe 14, which is connected to one of the end portions 12 of the metallic bladder element 10, runs to a topside surface not shown. The fluid pipe 14 is used for filling and expanding the metallic bladder element 10.

The metallic bladder element 10 may be connected via a supply pipe 16 to a pressurized fluid reservoir 18. Both the fluid pipe 14 and the supply pipe 16 may be equipped with valves such as a close-off valve 20 and a check valve 22.

When the close-off valve 20 is opened, pressurized fluid flows through the supply pipe 16 and valves 20, 22 from the pressurized fluid reservoir 18 and into the metallic bladder element 10.

When pressurized fluid is supplied to the metallic bladder element 10, the metallic bladder element 10 is expanded from its unexpanded position as shown in FIGS. 1 and 2, and to its expanded position as shown in FIG. 5.

In this expanded position the metallic bladder element 10 is normally permanently deformed relatively its unexpanded position.

When expanding the metallic bladder element 10 as shown in FIG. 5, the pipe 1 is forced against the anchor 6. The anchor 6 is then carrying any axial forces present in the pipe 10. Surfaces 24 of the anchor 6, see FIGS. 2 and 5, may have received friction enhancing treatment or be serrated according to known practice.

Now referring to FIG. 6, the pipe 1 is surrounded by more than one, here three metallic bladder elements 10.

In yet another embodiment, see FIG. 7, the metallic bladder elements 10 are overlapping another set of metallic bladder elements 10 a that are positioned between the metallic bladder elements 10 and the pipe 1.

FIG. 8 shows an embodiment where metallic bladder elements 10 are positioned in an elastic material 26 such as ethylene propylene diene monomer (EPDM).

When expanding the metallic bladder elements 10 the elastic material 26 will cause the annulus 8 to be closed.

In FIG. 9 the metallic bladder element 10 is given a helical form and surrounds the pipe 10 as a coil.

In another embodiment, see FIG. 10, the pipe 1 itself constitutes the anchor 6. The surface 24 of the pipe 1 may be tooted or have any suitable type of friction enhancing treatment, not shown.

In another alternative embodiment, see FIGS. 11 and 12, the metallic bladder element 10 is positioned between a first element 28 and a second element 30 of the anchor 6.

The first and second elements 28, 30 are mutually connected by a hinge 32 as shown in FIG. 11. A solid anchor 6 is provided on the opposite side of the pipe 1.

When the metallic bladder element 10 is expanded, the first element 28 is forced against the confinement 4, while the second member 30 is forced against the pipe 1. Axial forces are transferred between the first and second members 28, 30 through the hinge 32.

The metallic bladder element 10 may be filled with particles 34 as indicated in FIG. 3. When the metallic bladder element 10 is expanded, the particles 34 will move to fill the space available, thus preventing the metallic bladder element 10 from contracting if the pressure inside the metallic bladder element 10 should be reduced.

The particles 34 may prior to the expansion be positioned in the fluid pipe 14, the supply pipe 16, incompletely compressed voids in the expandable metallic bladder or any other suitable container not shown. 

What is claimed is:
 1. A method for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement, wherein the method comprises: providing an expandable metallic bladder element, that by use of a fluid is expandable between an unexpanded and an expanded position, in a sector of the annulus; and expanding the metallic bladder element.
 2. The method according to claim 1 wherein the method comprises providing a toothed or non-toothed anchor that in its engaged position, when the metallic bladder element is expanded, has an ability to transfer axial load between the pipe and the confinement.
 3. The method according to claim 1 wherein the metallic bladder element is expanded by use of a liquid.
 4. An apparatus for connecting a pipe to a confinement of a subsurface borehole where an annulus is formed between the pipe and the confinement, wherein an expandable metallic bladder element, that by use of a fluid is expandable between an unexpanded and an expanded position, is positioned in a sector of the annulus.
 5. The apparatus in accordance with claim 4 wherein the expandable metallic bladder element at expansion is permanently deformed.
 6. The apparatus in accordance with claim 4 wherein the expandable metallic bladder element is helically wound around the pipe.
 7. The apparatus in accordance with claim 4 wherein an anchor that in its engaged position has an ability to transfer axial load between the pipe and the confinement is positioned in the annulus, and where the metallic bladder element in its expanded position is engaging the anchor.
 8. The apparatus in accordance with claim 7 wherein the metallic bladder element and the anchor are positioned on opposite sides of the pipe.
 9. The apparatus in accordance with claim 7, wherein the metallic bladder element and the anchor are positioned on the same side of the pipe.
 10. The apparatus in accordance with claim 7, wherein the bladder element is positioned in the anchor.
 11. The apparatus in accordance with claim 7, wherein the anchor is made to engage by relative movement between at least a first and a second element of the anchor.
 12. The apparatus in accordance with claim 7, wherein the pipe itself constitutes the anchor.
 13. The apparatus in accordance with claim 7, wherein the anchor is made from an elastic material.
 14. The apparatus in accordance with claim 7, wherein the anchor is made from a metallic material.
 15. The apparatus in accordance with claim 7, wherein the anchor is made from a combination of elastic and metallic material.
 16. The apparatus in accordance with claim 7, wherein the anchor is made from a material that is swellable in a wellbore fluid.
 17. The apparatus in accordance with claim 4 wherein the metallic bladder element is positioned in an elastic material.
 18. The apparatus in accordance with claim 4 wherein a pressurized fluid reservoir is connectable to the metallic bladder element.
 19. The apparatus in accordance with claim 4 wherein the metallic bladder element is at least partly filled with particles. 